Cable

FIELD OF THE INVENTION

The present Invention relates to electrical cables and more particularly to electrical cables having a braided construction.

BACKGROUND OF THE INVENTION

It is known for electrical cables to include one or more braid of electrically insulating material for providing insulation for the electrical conductors of th cable. Furthermore braids of electrically conductive material may be formed around one or more insulated conductors to provide a shielding. Cables flaying multiple conductors may be produced, each being individually insulated, but such cables become more bulky as the number of conductors increases. The increase in bulk may be minimised by reducing the diameter of the conductors or the thickness of the insulation, but such measures can reduce the performance of the cable.

Cables having multiple conductors can also be provided by arranging the conductors side-by-side to form so called ribbon cables, but such cables can occupy a large area making them unsuitable for use in some applications. It can also be difficult to provide electromagnetic shielding for conductors of such cables.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a cable formed as an elongate body of electrically insulating material, said body having two or more electrical conductors disposed relative to a surface of the elongate body and arranged to extend along the length of the elongate body, wherein each of the at least two electrical conductors are arranged to remain separate from one another along the length of the elongate body.

Optionally, at least one of the two or more electrical conductors are at least partially enclosed by the electrically insulating material forming the elongate body. In this case, the elongate body may be of a first braided construction having at least one conductive element providing electrical continuity between one end of the elongate body and an other end of the elongate body and so provide one of the said electrical conductors. Furthermore, the first braided construction may have two or more conductive elements, each providing electrical continuity between one end of the elongate body and an other end of the elongate body and so each provide one of the said electrical conductors, each conductive element in the first braided construction being held in spaced relationship and therefore in electrical isolation from other conductive elements of the first braided construction by electrically insulating material of the braided construction.

The electrical conductors may be of a conductive metal, metal coated insulators or carbon fibre or conductive polymers.

The electrical insulators may be of nylon, polyamide, acetate, cotton or wool.

These and other aspects of the present invention appear in the appended claims which are incorporated herein by reference and to which the reader is now referred.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will now be described with reference to the Figures of the accompanying drawings in which:

FIG. 1<i>a </i>shows a first view of a portion of first embodiment cable made in accordance with the present invention;

FIG. 1<i>b </i>shows a cross sectional view taken across line I—I of FIG. 1<i>a; </i>

FIG. 2<i>a </i>shows views of portions of a second embodiment cable made in accordance with the present invention; and

FIG. 2<i>b </i>shows a cross sectional view of the second embodiment cable taken across portions as indicated by line II—II of FIG. 2<i>a.</i>

It should be noted that the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of the Figures have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar features in the different embodiments.

DETAILED DESCRIPTION OF THE PRIMARY EMBODIMENT

Referring to FIG. 1<i>a</i>, cable <b>10</b> is of a braided construction having a first conductive yarn <b>11</b>. second conductive yarn <b>12</b> and insulating yarns <b>13</b>. The first conductive yarn <b>11</b> and second conductive yarn <b>12</b> extend in the longitudinal direction of the cable <b>10</b> from one end to the other, each forming a helix. The first conductive yarn <b>11</b> and second conductive yarn <b>12</b> are held apart from one another and therefore in electrical isolation due to the interwoven insulating yarn <b>13</b> of the braiding. Hence, the helical path traced out by yarns of braiding is exploited to provide a multi-conductor electrical cable In the form of just one braid. By varying the braiding pattern used and the number of conductive yarns used, the number of separate electrical conductors provided can be increased beyond two. The insulating yarns <b>13</b> may progress in a helix in the same or opposite direction to that in which the conductive yarns progress.

Referring to FIG. 2, a second embodiment of the present invention is shown as cable <b>20</b> having three concentric braiding structures <b>21</b>, <b>22</b> and <b>23</b>, with braiding <b>21</b> innermost and braiding <b>23</b> outermost. Braiding <b>21</b> includes conductive yarn <b>11</b> forming a helix spiralling in a first direction as it travels along an axial direction of the cable. Braiding <b>22</b> is located between inner braiding <b>21</b> and outer braiding <b>23</b> and is formed of insulating yarns <b>13</b>. Outer braiding <b>23</b> includes conductive yarn <b>11</b> forming a helix spiralling in a second direction opposite to helix direction formed by conductive yarn <b>11</b> of braiding <b>21</b>. Hence yarn <b>11</b> of braiding <b>21</b> and yarn <b>11</b> of braiding <b>23</b> co-operate to form a twisted pair arrangement suitable for carrying electrical signals. Cable structures having more than three concentric braids may be provided.

Further braiding layers, each of which may include insulation and/or electrical conductors may be provided, as will be apparent to the person skilled in the art. Such braided constructions may also be used in conjunction with more traditional cable types. Optical fibre elements may be included in the cable.

The conductive yarns can be formed from conductive materials such as metal, carbon fibre conductive polymers or conductive polymers having a conductive property due to their composition. The conductive yarns may be formed by coating insulators such as polyamide coated with conductive materials such as nickel, copper, aluminium, gold and silver. Coating techniques include electroless plating. The insulating yarn <b>13</b> is made of insulating material such as nylon, polyamide, acetate, cotton and wool. Yarns may be monofilament or multifilament and each yarn may comprise more than one material. Each braid may comprise more than one yarn type. Conductive yarns may comprise a mixture of conductive and insulative materials.

While comparatively few yarns making up the braids are shown in the Figures of the drawing it will be apparent to the person skilled in the art that many more will normally be present.

From reading the present disclosure, other modifications will be apparent to persons skilled in the art. Such modifications may involve other features which are already known in the design, manufacture and use of cables, garments, upholstered articles and other soft furnishings and applications thereof and which may be used instead of or in addition to features already described herein.